JP2005134703A - Dew condensation state judging method and system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it possible to exactly judge whether dew condensation has occurred in image formation. <P>SOLUTION: The dew condensation state judging method performs: an image forming process of forming a halftone image by outputting a command of forming the halftone image for dew condensation judgment to an image forming section 101 in a non-heating state in which a photoreceptor is not heated; and an image density detecting process of detecting the image density of the actual image formed in the image forming section by an image formation command. Then a dew condensation state judging process is executed for judging whether there is the occurrence of the dew condensation from the relationship between the actual image density detected by the image density detecting process and the image density to be formed on the basis of the formation command. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrophotographic image forming technology such as a printer, a copying machine, and a fax machine, and relates to a method and an apparatus for determining whether or not condensation occurs in a photosensitive drum or the like, and also in a situation where condensation occurs. The present invention relates to an electrophotographic image forming apparatus capable of executing appropriate processing and obtaining a good image free from blur due to condensation and image flow when it is determined that the image is present.

In the electrophotographic image apparatus, when dew condensation occurs on the surface of the photosensitive drum, blurring, image flow, etc. occur in the formed image, and a good image cannot be obtained.
Therefore, conventionally, in an electrophotographic image forming apparatus, a heater is provided in a photosensitive drum or an intermediate transfer drum, etc., and when the apparatus is turned on, the heater is energized and constantly heated, thereby dew condensation. A configuration is adopted in which the surface of the photosensitive drum is maintained in a state where no occurrence occurs (this is a conventional technique and cannot indicate the prior art).

  On the other hand, a temperature / humidity sensor is provided in the image forming apparatus, and whether or not there is a possibility of dew condensation is judged based on the detection results of these temperature / humidity sensors. There is also a technique for making the timing appropriate (for example, Patent Document 1).

In other words, as described in the former prior art, the possibility of the occurrence of condensation is avoided by maintaining the heater in an always energized state, or the possibility of the occurrence of condensation is determined as shown in the latter prior art. The operation of the heater was controlled. Here, the basis of the determination is the detection result of the temperature / humidity sensor, and is not based on whether or not condensation has actually occurred on the photoreceptor.
JP-A-60-76759 (Claims, Fig. 3)

  However, if a predetermined heater is always energized for preventing condensation, power is consumed for preventing condensation even when no condensation occurs, which is wasteful. Furthermore, if the devices in the apparatus are always kept warm by the heater, the image carrier, developing device, toner and developer will be affected, and the characteristics of these devices and materials will change and their life will be shortened. The disadvantage is great.

  On the other hand, in the control using the detection result of the temperature / humidity sensor, the possibility of the occurrence of condensation is determined based on experience, etc. It is difficult to determine the occurrence of condensation. That is, since the humidity is low, condensation may occur even when the heater is in a non-energized state. If the image forming apparatus is continuously operated in such a situation, a defective image may be formed.

  An object of the present invention is to obtain a technique for accurately determining whether or not condensation has occurred in image formation, and in a situation where condensation has occurred, take appropriate measures along with the determination of condensation, blur, and image An object of the present invention is to obtain an electrophotographic image forming apparatus capable of obtaining a good image with no flow.

In order to achieve the above object, the characteristic means of the dew condensation determination state determination method in the first electrophotographic image forming apparatus includes:
In a non-heated state in which the photoconductor is not heated, an image forming process for forming a halftone image by outputting a command for forming a halftone image for dew condensation to the image forming unit, and an image by the image forming command. An image density detection step of detecting an image density of an actual image formed by the forming unit;
A dew condensation state determination step is performed to determine whether or not dew condensation has occurred based on the relationship between the actual image density detected in the image density detection step and the image density to be formed based on the formation command. There is to do.

The characteristic configuration of the first electrophotographic image forming dew condensation state determination apparatus using this dew condensation state determination method is that in a non-warmed state where the photoconductor is not heated,
Based on the instruction for forming a halftone image for dew condensation determination, the image forming means for forming a halftone image is provided,
Image density detecting means for detecting the image density of the formed actual image,
Condensation state determination means for determining whether or not condensation has occurred from the relationship between the actual image density detected by the image density detection means and the image density to be formed based on the formation command. There is.

  FIG. 3 schematically shows the state of blurring and image flow when condensation occurs on the surface of the photosensitive drum. In the same figure, (a) shows the movement state of the electric charge c on the photosensitive member 1 when the condensation w is generated, and (b) shows the situation where no condensation occurs.

  If dew condensation w is generated as shown in FIG. 6A, the movement of the electric charge c occurs, and the distribution of the toner t to be adhered by development is uneven.

  Therefore, in the first dew condensation determination of the present application, a predetermined halftone image formation command is generated, and the corresponding image is actually formed by the image forming unit. However, when condensation occurs, a decrease in image density appears due to the phenomenon seen in FIG. In view of this, the actual image density is detected, and in the dew condensation state determination step, for example, the presence or absence of dew condensation is determined by comparison with a density reduction threshold at which dew condensation is considered to occur.

  This determination method is based on the phenomenon that actually appears on the image side due to condensation without performing indirect determination such as determination based on the detection result of conventional temperature and humidity. Certain determinations can be made.

The characteristic means of the dew state determination method in the second electrophotographic image forming apparatus of the present application for achieving the above object is as follows:
An image forming process for forming a halftone image for determining condensation;
For the image formed in the image forming step, an image density detecting step for detecting an actual image density at two or more different parts, and
It is to execute a dew condensation state determination step of determining whether or not dew condensation has occurred from the actual image density detected at least one pair in the image density detection step.

Further, the present invention that uses this method, the characteristic configuration of the second electrophotographic image forming dew condensation state determination device, in a non-warming state where the photoconductor is not warmed,
Based on the instruction to form a halftone image for dew condensation determination, the image forming means for forming the halftone image is provided,
On the basis of the formation command, the actual image formed is provided with image density detection means for detecting the actual image density at two or more different parts,
The image density detection means includes at least a pair of condensation state determination means for determining whether or not condensation has occurred from the actual image density detected.

  In the above determination, the dew condensation was determined by comparing the image density to be formed according to the image formation command with the actually formed image density. However, in the halftone image actually formed, It is also possible to detect blur and image flow caused by condensation from the spatial disturbance of the image, that is, density change.

  That is, when a halftone image having a constant density for dew condensation determination is formed, and there are density differences between a plurality of locations in the image, it is determined that dew condensation has occurred.

  Also in this case, since the determination is performed while actually looking at the change in the determination density image, the dew condensation state can be detected with high reliability.

Now, the characteristic configuration of the electrophotographic image forming apparatus for obtaining a suitable image with the determination of the presence or absence of the occurrence of condensation determined as described above is as follows.
Comprising the dew state determination device of the first or second configuration of the present application,
When it is determined by the dew condensation state determination device that the dew condensation state is present,
There is provided dew condensation preventing means for operating the temperature adjusting means provided in the apparatus to maintain the apparatus in a non-condensing state.

  When it is determined by the dew condensation state determination device that dew condensation has occurred, dew condensation can be prevented from occurring by operating the temperature adjusting means to raise the temperature.

  Further, the temperature adjusting means is a heater provided for the photosensitive member or the intermediate transfer member, and the heater is operated when the dew condensation state determination device determines that the dew condensation state is present. It is preferable.

  By the operation of the heater, it is possible to reliably prevent the occurrence of condensation and to perform image formation without blurring or image flow.

On the other hand, as an electrophotographic image forming apparatus that achieves the above object,
Comprising the dew state determination device of the first or second configuration of the present application,
When it is determined by the dew condensation state determination device that the dew condensation state is present,
It is also preferable to employ a configuration including anti-condensation density adjusting means for operating the image density adjusting means provided in the apparatus so that the image density is obtained in a non-condensing state.

  When the degree of condensation is low and can be dealt with by density adjustment, it can be dealt with by operation control of equipment attached to the image processing apparatus other than the temperature adjusting means, although it is in the condensation area.

  By obtaining an electrophotographic image forming apparatus equipped with a determination device that uses the dew condensation state determination method of the present invention, it is possible to reliably detect dew condensation by confirming an image on an image carrier such as an intermediate transfer drum. A good electrophotographic system that can adopt a structure that works temperature control means, and can extend the life of machines and parts without adversely affecting development and others while minimizing the operation time of this kind of means such as heater An image processing apparatus could be obtained.

  An image forming apparatus to which the present invention is applied will be described based on the following embodiments.

[Schematic structure and operation of electrophotographic image forming apparatus]
FIG. 1 is a schematic configuration diagram of a color image forming apparatus 100 according to an embodiment of the present invention.
The color image forming apparatus 100 includes a central control unit CPU for controlling its operation, and operations such as image formation are based on an image formation command from the central control unit CPU.

  The image formation command from the central control unit CPU is at a predetermined timing at a photosensitive drum motor (not shown), charging device 2, laser writing device 3, developing device 4, and intermediate transfer drum motor (not shown). ), A motor (not shown) for the fixing device 9 or the conveyance roller 7, the registration roller 8, and the transfer roller 6.

  When this image formation command is output to each device at a predetermined timing, the photoconductor 1 is uniformly charged by the charging device 2 and then the image information of the image to be formed by the laser writing device 3. Accordingly, an electrostatic latent image is formed on the surface of the photoreceptor 1 by scanning exposure.

  In this embodiment, since color image formation is performed, the image information to be exposed is single-color image information obtained by separating a desired full-color image into color information of yellow, magenta, cyan, and black. The electrostatic latent image thus formed is visualized as described below.

  The yellow electrostatic latent image formed on the photoreceptor 1 is developed by the yellow developing device 4-1 and then transferred onto the intermediate transfer drum 5. Next, the magenta electrostatic latent image formed on the photosensitive member 1 is developed by the magenta developing device 4-2 and then transferred onto the intermediate transfer drum 5. Similarly, cyan and black electrostatic latent images formed on the photosensitive member 1 are developed by a cyan developing device 4-3 and a black developing device 4-4, and then sequentially transferred to an intermediate transfer drum 5. Overprinted on top.

  The full-color image formed by being transferred onto the intermediate transfer drum 5 in this way is transferred onto the transfer material (not shown) transferred to the transfer section A via the transfer roller 7 and the registration roller 8. Is transcribed by. After the transfer is completed, the image on the transfer material is fixed to the transfer material by the fixing device 9 and is discharged to the paper discharge unit 10.

  The above is the procedure when a predetermined image is formed by the electrophotographic method in the color image forming apparatus.

[Detection of formed image density]
As shown in FIG. 1, the image forming apparatus 100 of the present application is provided with an image density detection device Sa for detecting the density of an image formed on the intermediate transfer drum 5. As is well known, the image density detection device Sa is configured to include a light emitting unit Sa1 and a light receiving unit Sa2 as a pair, and is formed on the intermediate transfer drum by irradiating light from the light emitting unit Sa1. The reflected light from the image is received by the light receiving unit Sa2, and the image density is detected from the amount of received light.

  The image density detection device Sa is used for determining the presence or absence of the occurrence of condensation, which is a characteristic configuration of the present application, and for correcting the image density of the formed image in a situation where the photoconductor is heated and no condensation occurs. Also used for.

  Hereinafter, an apparatus configuration provided in the image forming apparatus 100 of the present application for preventing condensation will be described, and a method for determining the occurrence of condensation unique to the present application and an apparatus configuration thereof will be described.

[Configuration to prevent condensation]
Heater heating As shown in FIG. 1, a heater H is provided inside the photosensitive drum 11, and when the heater H is energized, a predetermined amount of condensation does not occur on the surface of the photosensitive member 1. It is comprised so that it can maintain in a heating state.
The operation control of the heater H is also based on the operation command from the central control unit CPU described above.

  In the case of the present application, normally, the heater H is maintained in a non-energized state, and when it is determined that condensation has occurred, the heater H is energized and the energization is maintained in a state where image formation is continuous. Then, energization is stopped after a predetermined waiting period.

  In this example, the heater H is housed in the photosensitive drum 11. However, if the drum surface can be substantially warmed, there is no need to be in the drum, and the vicinity of the outside of the drum. A heater may be provided.

  Furthermore, it is not always necessary to directly warm the object to be warmed, and a heater may be provided on the intermediate transfer drum 5 that is in contact with the photosensitive drum 11 to indirectly warm it.

(B) Temperature and humidity adjustment in the apparatus Further, as shown in FIG. 1, exhaust fans Fa and Fb and an intake fan Fc are provided at predetermined positions of the apparatus. By providing the exhaust fan Fb in the vicinity of the fixing device 9 and further providing the exhaust fan Fa on the upper side of the internal space of the apparatus and on the right side, the exhaust fan Fb is relatively high by exhausting from the internal space. Can exhaust the temperature internal air.

  On the other hand, the intake fan Fc is on the upper side of the internal space of the apparatus, in the vicinity of the paper discharge unit 10, and on the opposite side of the exhaust fan Fa with respect to the exhaust fan Fb (ie, on the left side of the internal space of the apparatus). For example, the temperature of the internal space can be adjusted by sucking cold outside air.

  Further, temperature detection means Sb and humidity detection means Sc are provided in the space above the housing that is not affected by heat from the fixing device 9, and the temperature and humidity inside the apparatus are adjusted at an appropriate time such as after the power is turned on. The detected operation control of the fan F is also based on the operation command from the central control unit CPU.

  As described above, in the present application, means for controlling the temperature of the internal space of the apparatus or the temperature / humidity of a portion related to dew condensation by its operation is called temperature adjusting means.

[Halftone image formation for condensation determination]
The color image forming apparatus 100 employs a configuration that determines whether or not condensation has occurred at an appropriate time after the apparatus is turned on or when returning from the power reduction mode. In this state, the heater H provided in the photosensitive drum 11 is not energized.
Hereinafter, this configuration will be described together with the structure of software stored in the central control unit CPU.

  The image forming apparatus 100 of the present application can form an image with a predetermined density in the image forming unit A based on an image forming command. Therefore, the apparatus of the present application uses this apparatus configuration to issue a formation instruction for forming a halftone image for dew condensation determination (for example, an image with ID (image density) = 0.4 as an example). The image density thus detected is detected by the image density detection device Sa described above.

  That is, as shown in FIG. 1, the central control unit CPU is provided with a dew condensation determination image generating means Ca. By means of this means Ca, the devices in the image forming unit 101 are halftone for dew condensation determination. An image formation command is generated and output.

  On the other hand, on the side of the image density detection device Sa, the density of the image actually formed on the intermediate transfer drum 5 is detected based on the generation command.

  In the storage means M in the central control unit CPU, condensation occurs in the relationship between the image density of the image to be formed based on the formation command and the image density of the actually obtained image. Information that is classified based on the relationship with the situation that is not stored is stored, and when the actual image density is below a predetermined threshold value, a condensation determination table is provided that can determine that condensation has occurred. Yes. This table is, for example, according to the temperature and humidity in the internal space of the apparatus.

  Then, when the detected image density is lower than a predetermined threshold (when the density is lower than the predetermined value) by the determination means Cb provided in the central control unit CPU, condensation occurs. Is output. If it is higher than the threshold and close to the target concentration, it is determined that no condensation has occurred.

[Measures when condensation occurs]
When it is determined that condensation has occurred as described above, the heater H provided inside the photosensitive drum 11 is heated in an energized state (ON state), and condensation on the drum is performed. It is supposed to prevent the occurrence of

  Now, after the energization of the heater H is maintained for a predetermined time, in a normal case, the process shifts to image formation. When further image density correction is performed, a so-called density correction test batch image is formed, and this is performed. If the image density is not appropriate by reading with the image density detecting device Sa, the bias value of the developing device (4-1 to 4-4) or the exposure amount of the laser writing device 3 is changed to set the image density to an appropriate value. Set to be.

  As a result, in the electrophotographic image forming apparatus 100 of the present application, condensation is effectively generated by causing the heater H to work only in a situation where condensation is truly generated and the image density is lowered with respect to the target image density. While preventing and maintaining an economical and reasonable operating state, it is possible to obtain a good image without blurring or image flow.

In the following, we will list the verification examples of changes in image density when the inventors performed the determination of the occurrence of condensation using the method of the present application, divided into cases where no condensation has occurred and cases where condensation has occurred. I will explain.
a When no condensation occurs Environmental conditions Temperature 30 ° C Humidity 60%
Image formation command condition Command to form gray image with ID = 0.4 Image density of actual image ID = image with image of 0.3 to 0.4 When condensation occurs Environmental condition Temperature 30 ° C Humidity 80%
Image formation command condition Command to form gray image with ID = 0.4 Image density of actual image Decrease to ID = 0.15 c Example of determination condition to determine that condensation has occurred Image formation command condition ID = 0 .4 Gray image formation command Condensation occurs when the image density of the actual image is lower than ID = 0.2. No condensation occurs when the image density of the actual image is higher than ID = 0.3

  Here, as the halftone image for dew condensation determination, an ID = 0.4 is used, but an ID = 0.4 to 0.7 range can be used. When the temperature drops by about 0.2, the heater operation can be surely executed. When the degree of this decrease is low (decrease degree: ID is about 0.1), it can be adjusted separately as described below.

[Another embodiment]
(1) In the above-described embodiment, the occurrence of condensation is determined from the image density based on the halftone image formation command based on the degree of decrease in the image density of the actually obtained image. In the case of the present application, if the target image once formed as an electrostatic latent image can be detected to be distorted (blurred or flowed) by the influence of condensation until the final transfer, evaluation / determination of condensation Is possible. Therefore, as shown in FIG. 2, it is detected whether density change has occurred in two or more locations on the intermediate transfer drum 5 in the drum rotation direction, and dew condensation occurs when the degree of disturbance exceeds a threshold value. You may determine that it has occurred.

When this type of technique is employed, a predetermined halftone image is formed, the density is detected at at least two locations in the drum rotation direction, and the determination is made based on the degree of density change. .
In addition, the image density detection may be performed at any stage as long as it can be detected.

(2) In the above embodiment, when it is determined that condensation has occurred, the heater H in the photosensitive drum or the intermediate transfer drum is operated. The operation of the heater may be started. In addition, a belt or the like may be used instead of the intermediate transfer drum, and a mechanism responsible for image transfer interposed between the photosensitive drum and the transfer roller is referred to as an intermediate transfer member.
In addition, if there is a possibility that condensation has not occurred significantly and condensation has occurred, but it may be absorbed by normal density correction, adjustment of the primary transfer current (voltage) and secondary transfer current (voltage) is possible. Further, density adjustment may be performed on the image density adjustment side such as development bias, surface potential, grid voltage, and laser power adjustment. That is, it is possible to absorb the problem of dew condensation by adjusting the operation of the image density adjusting means. The means for performing this operation adjustment is referred to as dew condensation countermeasure density adjustment means in the present application.

  In the electrophotographic image processing apparatus, the occurrence of condensation can be determined with sufficient reliability on the basis of density, and the image formed by the image processing apparatus can be free from blurring or flowing.

The figure which shows schematic structure of the electrophotographic image forming apparatus which concerns on this application The figure which shows schematic structure of another embodiment of the electrophotographic image forming apparatus which concerns on this application Explanatory drawing explaining the principle that blur, image flow, etc. occur with the occurrence of condensation

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charging apparatus 3 Laser writing apparatus 4 Developing apparatus 5 Intermediate transfer drum CPU Central control apparatus Ca Condensation determination image generation means Cb Determination means H Heater M Storage means Sa Image density detection apparatus

Claims (7)

In a non-heated state in which the photoconductor is not heated, an image forming process for forming a halftone image by outputting a command for forming a halftone image for dew condensation to the image forming unit, and an image by the image forming command. An image density detection step of detecting an image density of an actual image formed by the forming unit;
A dew condensation state determination step is performed to determine whether or not dew condensation has occurred based on the relationship between the actual image density detected in the image density detection step and the image density to be formed based on the formation command. A dew condensation state determination method in an electrophotographic image forming apparatus. In a non-warmed state where the photoconductor is not heated, the image forming means for forming a halftone image based on a halftone image formation command for dew condensation determination is provided.
Image density detecting means for detecting the image density of the formed actual image,
Condensation state determination means for determining whether or not condensation has occurred from the relationship between the actual image density detected by the image density detection means and the image density to be formed based on the formation command. Condensation state determination device for electrophotographic image formation. An image forming step for forming a halftone image for dew condensation determination in a non-warmed state where the photoconductor is not heated;
For the image formed in the image forming step, an image density detecting step for detecting an actual image density at two or more different parts, and
A dew state determination method in an electrophotographic image forming apparatus that executes a dew state determination step for determining whether or not condensation has occurred from at least one pair of the actual image densities detected in the image density detection step. In a non-warmed state where the photoreceptor is not heated, the image forming means for forming the halftone image based on a command for forming a halftone image for dew condensation determination is provided.
On the basis of the formation command, the actual image formed is provided with image density detection means for detecting the actual image density at two or more different parts,
A dew state determination apparatus for electrophotographic image formation, comprising dew state determination means for determining whether or not dew condensation has occurred from at least one pair of the actual image densities detected by the image density detection unit. The dew condition determination device according to claim 2 or 4,
When it is determined by the condensation state determination device that the condensation state is present,
An electrophotographic image forming apparatus provided with dew condensation prevention means for operating a temperature adjusting means provided in the apparatus to maintain the apparatus in a non-condensation occurrence state where no dew condensation occurs on the photosensitive member. 6. The heater according to claim 5, wherein the temperature adjusting unit is a heater provided for the photosensitive member or the intermediate transfer member, and the heater is operated when the dew condensation state determination device determines that the dew condensation state is present. An electrophotographic image forming apparatus. The dew condition determination device according to claim 2 or 4,
When it is determined by the condensation state determination device that the condensation state is present,
An electrophotographic image forming apparatus comprising anti-condensation density adjusting means for operating an image density adjusting means provided in the apparatus to obtain an image density obtained in a non-condensing state.

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